Doc007 Posted July 14 Share Posted July 14 Is the removal/installation of a brake light switch a job of moments or something to regret you started? Remove pedal box and whip it out? A friend has really dim brake lights that sometimes flicker. They are the new LED type and I’d like to try swapping his brake light switch for mine to see if it is faulty as, because it is both lights, I assume it’s either the switch or a poor earth. Does anyone know where the earth is for the brake lights? Anything else it might be? 2020 420 SV. Link to comment Share on other sites More sharing options...
K7 VCT Posted July 14 Share Posted July 14 Just touch his brake lights connectors together to bypass his switch..... Sounds like a poor earth. Jonathan, will be able to send you a wiring diagram Link to comment Share on other sites More sharing options...
Doc007 Posted July 14 Author Share Posted July 14 40 minutes ago, K7 VCT said: Just touch his brake lights connectors together to bypass his switch..... Sounds like a poor earth. Jonathan, will be able to send you a wiring diagram Ah, clever! Unlike me with electrics. A wiring diagram may be lost on me unless it show exactly where the earth is! But I’ll take a look … 1 Link to comment Share on other sites More sharing options...
Leadership Team 700newtons Posted July 14 Leadership Team Share Posted July 14 Swapping the brake light switch is straightforward. It's also well worth doing - here is one of the many threads about it in the forum. Link to comment Share on other sites More sharing options...
MattB Posted July 14 Share Posted July 14 (edited) It could be that the plate that depresses the brake switch plunger isn’t properly set, ie it isn’t fully depressing the plunger. Easy enough to check with the pedal box cover off. MattB Edited July 14 by MattB Correction Link to comment Share on other sites More sharing options...
Jonathan Kay Posted July 14 Share Posted July 14 I’m on a ‘phone so pls pardon brevity. Yes, check plunger action. You can open the standard switch and try to improve the contact, but there’s a spring just waiting to make a bid for freedom. Do it in a box. But there’s a much better switch available: lots of references in the archives. Jonathan Link to comment Share on other sites More sharing options...
Doc007 Posted July 14 Author Share Posted July 14 Thanks chaps. And whereabouts is the earth? Link to comment Share on other sites More sharing options...
Jonathan Kay Posted July 14 Share Posted July 14 IIRC it switches the live feed. And uses the common earth near the lamp unit. Jonathan Link to comment Share on other sites More sharing options...
BigCol Posted July 14 Share Posted July 14 (edited) 23 hours ago, Jonathan Kay said: IIRC it switches the live feed. And uses the common earth near the lamp unit. That ⬆️ As above, remove the cover, short the switch’s terminals and see how the lights look. If the same, then issue is unlikely to be switch but earth-related. If brighter, then the switch probably isn’t making full contact. Edited July 15 by BigCol Link to comment Share on other sites More sharing options...
John Vine Posted July 15 Share Posted July 15 If you do need to replace the switch, the Intermotor 51690 is a much better alternative. The other approach is to reduce the current flowing through the switch (and the potential for arcing) by fitting a relay. Of course, your friend's LED lights mitigate the need for that. JV Link to comment Share on other sites More sharing options...
Doc007 Posted July 15 Author Share Posted July 15 On 14/07/2024 at 18:28, Jonathan Kay said: IIRC it switches the live feed. And uses the common earth near the lamp unit. Jonathan Thanks Jonathan. Sorry to be a PITA but where is the common earth near the lamp unit. Link to comment Share on other sites More sharing options...
Jonathan Kay Posted July 16 Share Posted July 16 That should be a black wire from the loom to the multi-way connector near the lamp unit. But I don’t know where the other end connects to the body/chassis. Might be at the front of the transmission tunnel. if you suspect a bad earth then this is the type of fault where checking continuity is NOT enough. You need to measure resistance or test with a temporary wire to a known good earth. Jonathan Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now